Raonic defeated Andreas Seppi 6-4, 6-4, 3-6, 7-5 on Sunday and Canada advanced to the World Group semifinals for the first time by defeating Italy 3-1 in their quarter-final tie.
Raonic said he wasn't particularly concerned that he had let Seppi back into the match when he dropped the third set to his Italian opponent.
"It wasn't like I got completely outplayed in the set," he said. "He just converted his chances better than I did. I just kept plugging away. I'm looking forward to the next series in Serbia. It's going to be an exciting opportunity."
Canada will next face Serbia in the World Group semifinals in September.
Serbia, which features the world's top player Novak Djokovic, wrapped up its quarter-final tie with the U.S. on Sunday when Djokovic defeated Sam Querrey 7-5, 6-7 (4), 6-1, 6-0 to give the Serbs an unbeatable 3-1 lead in the series played in Boise, Idaho.
Canada had never been to the Davis Cup quarter-finals in the modern era until it upset Spain in February.
Raonic's win ran the Thornhill, Ont., native's personal winning streak of Davis Cup singles matches to seven straight. His overall record for Canada is now 12-4, 10-3 in singles and 2-1 in doubles.
Canadian captain Martin Laurendeau marvelled how far his team has come in just the past few years, when just the thought of getting into the World Group seemed like a major challenge.
"I remember just three years ago and Milos was playing Davis Cup for us against the Domincan Republic in Toronto," said Laurendeau. "To be down like we are now to the (World Group) final four is an incredible honour. A lot of Canadian team captains before me have tried to get to where we are now."
Canada's victory over Spain at the same University of British Columbia venue in early February was a true upset with Spain ranked No. 1 in the world in Davis Cup — although the Spaniards were missing a couple of their top guns. But the win over Italy, on paper at least, was a true toss up.
Raonic and Seppi were virtually tied in the world rankings and Italy's second singles player, Fabio Fognini, held a huge ranking advantage over Canada's No. 2 Vasek Pospisil. And the doubles — which Canada won in five tense sets Saturday — also looked like a "pick-em" matchup.
But on a deeper level Canada had many things going its way. First, was the home country's comfort level with the venue. It was the third tie involving Canada at the UBC arena in the past 13 months.
Then there were the choice of playing surface (Premier indoor hard court) and balls (Yonex Tour 1), which in both cases favoured Canada, whose players prefer faster courts and livelier balls.
The big-serving Raonic took full advantage of all those factors Sunday in downing Seppi.
He won the first two sets fairly handily, but Seppi battled back to take the third 6-3. The decisive fourth set went without a break until Seppi, serving at 5-6 to get into a tie-break, fell into a hole. He battled back to 15-40. But then the Italian ace netted a slice backhand attempt on Raonic's first match point to end the drama.
Seppi pointed out the surface Canada chose for the tie is so quick that it is rarely used on the pro tour.
"I didn't have a chance to place my racquet on many serves those first two sets," he said. "In a tournament you don't often play on a surface like that. It's difficult to get your rhythm."
But Italian captain Corrado Barazzutti said that's all fair play in Davis Cup.
"I think Canada chose the best surface for their players," he said.
The semifinal will be played in Serbia where it will be Canada's opponent's terms to dictate the terms of the competition. Canada has actually been incredibly fortunate in that regards, having been favoured with four straight home-soil ties. That string will end in September.
With the series decided, both team captains agreed to cancel Sunday's scheduled second singles.
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